Kinematic calibration method for Stewart parallel robot

Abstract

The invention relates to a kinematic calibration method for a Stewart parallel robot. According to the kinematic calibration method for the Stewart parallel robot, model simplification is achieved according to a coordinate system establishment rule to obtain a minimum to-be-identified parameter set, and then a nonlinear kinematic model of the parallel robot is obtained; any fixed measurement equipment and any three fixed target point are adopted, and the posture of a robot fixing platform relative to a measurement coordinate system, the positions of the target points relative to a movable robot platform coordinate system, and the like are used as to-be-identified parameters, so that a simple measurement process is achieved, and operation is easy; the nonlinear kinematic model of the parallel robot is combined with a measurement process model to obtain a nonlinear identification model of a whole calibration system; and the resolution of a nonlinear equation system is converted into theresolution of a nonlinear optimization problem. By the adoption of the kinematic calibration method for the Stewart parallel robot, model establishment is achieved through the complete minimum parameter set, model calibration is easier, and true parameters of the robot are directly resolved on the basis of a nonlinear optimization idea; and the kinematic calibration method has the advantages thatoperation is easy, user interfaces are friendly, and the practicability is high.

Description

technical field [0001] The invention belongs to the technical field of advanced manufacturing and automation, and relates to a robot calibration method, in particular to a Stewart type parallel robot kinematics calibration method. [0002] technical background [0003] As a multi-loop closed-chain mechanism, a parallel robot has the advantages of high load, high stiffness, and high speed, and has been well applied in the fields of motion simulation, processing and manufacturing, and high-speed assembly. Especially in the field of processing that requires high precision and rigidity, parallel mechanisms are often used to build parallel machine tools. Although the working space of the parallel mechanism is small, compared with the series mechanism, there is no accumulation of joint errors in the parallel mechanism, and the accuracy is relatively high. Nevertheless, people still hope to further improve its precision to meet more precise processing requirements. According to th...

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Problems solved by technology

[0005] In view of the inaccurate position of the connection points between each branch of the parallel robot and the upper and lower platforms, and the deviation between the branch movement direction and the connection line of the node, the problem that an accurate kinematics model cannot be obtained, the technical problem to be solved by the present invention is to use Stewart type parallel Mechanism as the object, providing a simple and practical parallel robot calibration method

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